1. Field of the Invention
The present invention relates primarily to centrifugal throwers, which may be used on swivelloaders, swivelpilers, box car loaders, pilers, ship trimmers and the like.
2. Background Information
Generally, centrifugal throwers provide the function of delivering a large quantity of loose material, such as wood chips or other particulate or granular material, into a large container, such as the cargo hold of a vessel, and ensuring that the material is distributed substantially evenly throughout substantially the entire container. The basic components of typical centrifugal throwers are outlined in the following publications of Stephens-Adamson, Inc.: "Ship Trimmers" and Catalogue C-460, entitled "Centrifugal Thrower Units". As shown in those publications, a centrifugal thrower typically includes a chute structure for receiving material from another source and a belt unit, with an endless belt carried by a pair of spaced drums or pulleys. The chute is generally configured to feed material downwardly to the belt unit. Because material fed in this manner typically falls a considerable distance prior to reaching the belt, it typically reaches the belt at a considerable velocity.
Idler discs engaging with the moving belt form a curved pathway for the material to follow. The curved pathway essentially allows for the high velocity of the delivered material to be retained; in this manner, little, if any additional velocity generally needs to be imparted by the belt. Thus, because of the high discharge velocity, the delivered material can be thrown a substantial distance.
Centrifugal throwers, especially ship trimmers, may also include a bypass chute, branching off from the main chute, to allow delivered material to bypass the belt unit and be delivered generally directly downwardly. Generally, in such circumstances, the belt unit of the thrower apparatus is shut off.
Several U.S. patents disclose known centrifugal throwers capable of adjusting the angle of throw, or the initial angle at which material is discharged from the belt. For example, U.S. Pat. No. 3,136,405 to Kulla discloses a bulk material loading and trimming machine in which, apparently, the trajectory of discharged material can be adjusted during operation. U.S. Pat. No. 3,039,594 to Lucas discloses an apparatus for throwing discrete substances, such as sugar, grain and the like, in which the position of the discharge pulley, or the pulley at which material is discharged from the belt, can be adjusted in order to change the angle of trajectory of the material being thrown. Additionally, U.S. Pat. No. 3,179,235, also to Lucas, shows a type of trimming apparatus in which it is also possible to adjust the angle of trajectory of discharged material.
U.S. Pat. No. 4,144,962 to Ide shows a loading trimmer in which the attitude of the entire belt unit, including the pulleys, is adjustable. Thus, the entire structure of belts and pulleys, and the belt motor, undergoes a rocking motion about the idler discs. However, because the entire belt unit, including both sets of pulleys, and the belt motor needs to be displaced, a potentially costly driving system for affording such displacement is usually needed. Also, a problem encountered here, as well as with other known devices, is that the range of angles of trajectory afforded thereby may not be as great as is desired for the application at hand.